1. Field of the Invention
The present invention relates to waste processing and recovery of useful products. Specifically, the invention is directed to metal and energy recovery from metal working fluid such as cutting oil waste.
2. Description of the Related Art
Machines are typically used to shape metal objects. For example, a lathe is a machine in which a piece of metal to be shaped is rotated about a horizontal axis and shaped by a fixed tool. Working or shaping a piece of metal results in heat. Specifically, heat is generated at the point of contact between the tool and the metal object to be shaped. To avoid unnecessary wear on tool parts the tool part and/or metal to be shaped are typically cooled using a working fluid. The working fluid is sometimes referred to as a metal working fluid or cutting oil. Such fluids both lubricate and cool the tool and metal being shaped.
Cutting or metal working fluids (hereinafter referred to as metal working fluids) typically contain at least one organic or hydrocarbon based lubricant. As the metal is shaped metal shavings are generated and are sometimes carried away with the metal working fluid. The metal working fluid is open to the air and is populated by bacteria from the air and from dirty work surfaces. Bacterial contamination of the metal working fluid can lead to health and safety issues since the metal working fluid can form a spray at the interface between the tool and the metal being shaped. In addition, the bacteria can use the hydrocarbon component of the lubricant in the metal working fluid as a food or carbon source leading to serious degradation in the lubricating properties of the metal working fluid. Eventually, the metal working fluid must be replaced with fresh metal working fluid. In turn, this generates a serious waste disposal problem.
A review of the prior art follows.
U.S. Pat. No. 4,624,417, issued Nov. 25, 1986 to Gangi, describes a process for converting solid waste and/or sewage sludge into a chemical intermediate substrate for production of energy and/or separate non-energy related by-products. The process of this invention integrates technologies for slurry production and material recovery; slurry demineralization and heavy metal recovery; formation and storage of chemical intermediate substrate; its dewatering; its processing into various energy sources such as solid carbon fuel, steam, or methane gas; and/or production of non-energy by-products such as cement board, gypsum fiber board, or agricultural products.
U.S. Pat. No. 5,009,672, issued Apr. 23, 1991 to Ruffo, et al., describes a process for handling solid urban waste (“SUW”). Ferromagnetic material is removed from the SUW and the SUW is subsequently subjected to high-pressure compression inside a screening press or the like, so as to separate biodegradable organic material from the dry material intended to form the combustible material, then subjecting the organic material to a process of anaerobic fermentation to generate a biogas, which can be used directly for producing electric power or for other uses. The residuals of fermentation in the form of humus is refined and screened to recover light materials.
U.S. Pat. No. 4,409,020, issued Oct. 11, 1983 to Holman et al., describes a metal recovery process. Metals such as Co, Ni, Cu and Fe, are recovered from a magnet alloy grinding sludge by: (1) treatment with an organic solvent to remove a major portion of sulfur and oil contaminants, (2) drying, grinding, sizing and magnetic separation to remove a major portion of grinding media contamination, (3) controlled oxidation-roasting to selectively remove residual sulfur and carbon, and (4) gaseous hydrogen reduction to deoxidize metal values.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a magerle metal waste recovery process solving the aforementioned problems is desired.